Review of the genus Chinoperla Zwick , 1980 ( Plecoptera : Perlidae : Perlinae ) from China

1,3 Guangxi key laboratory of Agric-Environment and Agric-Products Safety and National Demonstration Center for Experimen tal Plant Science Education, Agricultural College, Guangxi University, Nanning, Guangxi 530004, China. 2 Henan Institute of Science and Technology Herbarium, Xinxiang, Henan 453003, China. 1,4 Department of Plant Protection, Henan Institute of Science and Technology, Xinxiang, Henan 453003, China. 5 Department of Zoology, Eszterházy Károly University, Leányka u. 6, Eger H-3300, Hungary.

were transferred to the genus (Zwick 1980(Zwick , 1982. Later on, Chinoperla nigrifrons (Banks, 1939) was also added to the genus, transfered from Ochthopetina Enderlein, 1909, a syn onym of Neoperla Needham, 1905(Sivec et al. 1988). The aedeagus of C. nigrofl avata, the type species of the genus, was not everted and described in the original description, and it remained poorly known. Chinoperla furcomacula has been regarded as a synonym of C. nigrifrons by Sivec et al. (1988), while Sivec & Zwick (1989) raised questions about their synonymy due to the diff erent female genitalia. Both species have been described or briefl y commented on in several studies, but their aedeagus still has not been fully described (Wu , 1973Zwick 1980Zwick , 1982Sivec et al. 1988;Sivec & Zwick 1989). Chino perla currently contains 15 known species, restricted to Southern Asia (Yang & Li 2018;DeWalt et al. 2021). Two Chinese species, C. biprojecta Wang, 2019 andC. mengmanensis Qian & were recently described from Hainan and Yunnan, respectively. Therefore, up to now, there are four species of Chinoperla known from China.
In the present paper, we present a review of six species of Chinoperla from China. A redescription and detailed comments on C. nigrifrons are provided. We support the fact that that holotype C. furcomacula is conspecifi c with C. nigrifrons. Chinoperla changjiangensis sp. nov. is described from both sexes and eggs, collected in the Bawangling National Nature Reserve of Hainan Province. The male paratype of C. nigrifrons is proved to be distinct from the holotype, and belongs to C. changjiangensis sp. nov. Chinoperla gorohovi Sivec & Stark, 2010 from Mountain Nankunshan of Guangdong Province is newly reported from China with a redescription of the male, while the female and egg are described for the fi rst time. A provisional key to the presently known Chinese species of the genus is also given.

Materi al and metho ds
Studied specimens are deposited in the Entomological Museum of China Agricultural University, Beijing (CAU), the Henan Institute of Science and Technology, Xinxiang (HIST), Henan Province, the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing (IZCAS) and the Museum of Comparative Zoology, Harvard University, Cambridge, Massac husetts (MCZ), respectively, as indicated in the text. New specimens were collected using sweep nets or by hand, and stored in 75% ethanol. Color illustrations were made w ith the aid of an Imaging Source CCD attached to a Leica M420 microscope in the HIST, further color illustrations were made with a Leica C camera via the lens of an Olympus SZX7 microscope in the IZCAS. At the MCZ, the color illustrations were made with a Leica C camera via the lens of a Wild Photomakroskop M400. Further line drawings were made by free hand. All pictures were adjusted and assembled into plates with Adobe Photoshop CC 2019. Abdomens of the specimens were c leared in 10% NaOH. The morphological terminology follows that of Lü et al. (2019a) and Sivec & Zwick (1989).

Remarks
This species is characterized by the median sclerite of tergum 9 forming an inverted triangle bearing two fi nger-shaped posterolateral projections. The aedeagus of the present specimen agrees well with the type material.

Diagnosis
Head with a dark bro wn ce ntral spot su bdivided by the lighter M-line. Male tergum 9 with a trumpet-shaped median sclerite. Aedeagal tube with a T-shaped sclerotized dorsal marking. Aedeagal sac dorsoapically with a low membranous median lobe and fringed with several small spines at its margin; ventrally with a rectangular sclerite armed with three to fi ve spines arranged in a comb-shape; ventrolaterally with two subapical groups of small spines; apically with a long straight spine and a large spinose lobe; laterally with six large curved spines on each side. Posterior margin of female sternum 8 slightly produced, forming a triangular subgenital plate with a shallow mesal notch. Eggs brown, oval shaped with small collar.

Etymology
The name refers to the type locality, Changjiang Li Autonomous County.

A
(Figs 1A, 3A-C). General color pale brown. Forewing length 6.8 -7.0 mm, hindwing length 6.1-6.2 mm. Head pale brown, with a dark brown central spot subdivided by the lighter M-line; biocellate, ocelli about 3 diameters apart of each other but still closer to each other than to the compound eye; antennae brownish. Pronotum pale brown, trapezoidal, with o bscure paler rugosities and darker midline; anterior corners pointed but posterior corners obtuse. Legs pale brown, joints darker; wings subhyaline and yellowish brown, veins brown, Sc of forewing short, typical of the genus; cerci pale.

A
(Figs 1B-D, 3D-E). Sterna 3-5 with hair brushes. Dark median sclerite of tergum 9 trumpetshaped, about half as long as the segment, heavily sclerotized, distally forked with two blunt points. Hemitergal processes slender, about 2.5 × as long as basal width; triangular in lateral view; basal callus fully covered with sensilla basiconica.

A
(Figs 2, 3F). Aedeagal tube dorsally sclerotized, sclerite forming a T-shaped marking. Sac as long as the tube when fully everted, distinctly curved dorsad; dorsoapical surface with a low membranous median lobe and several small spines located in a fringe; a single large straight spine about as long as ⅓ aedeagus length and a large spinose lobe medially at apex, directed dorsally; ventral surface with a large basal patch of spinules, and a rectangular sclerite armed with three to fi ve spines arranged in a combshape; two subapical groups of small spines located in ventrolateral surface; lateroapical part with six larg e curved spines on each side. . Several mature eggs were dissected from female terminalia. Oval-shaped with obscure opercular line, widest in subequatorial area towards opercular end. Anchor absent from the studied eggs. Collar short and button-shaped. Chorionic surface b rown with heavy and distinct punctuations throughout. Micropylar orifi ces sessile, much larger than punctuations, set on subequatorial line.

Distribution
China: Hainan Province. Known only from the type locality.

Remarks
One of the male paratypes of C. nigrifrons (Banks, 1939) belongs to C. changjiangensis sp. nov. The aedeagal tube of this male had been damaged before our examination. After further gentle squeezing, the sac was nearly fully everted but quite distorted; the observable armatures are illustrated on Fig. 3F. Since the aedeagus is partly damaged, we are not sure whether additional spines remained hidden and were not disclosed in the present study, hence the specimen is not designed as a paratype of C. changjiangensis sp. nov. The new species and C. biprojecta Lü, Yan, Li & Wang, 2019 are most similar in head pattern, hemitergal processes, aedeagal tube, and aedeagal sac that is apically armed with a long spine, a large lobe and a comb-shaped sclerite. However, C. changjiangensis sp. nov. is easily distinguishable from the latter by the trumpet-shaped median sclerite of tergum 9 and the comb-shaped sclerite of the aedeagal sac with fi ve short spines arising from the rectangular sclerite. In C. biprojecta, the median sclerite of tergum 9 is triangular with two fi nger-shaped projections bearing several black tiny warts, and the comb-shaped sclerite has four longer spines extending from the triangular basal sclerite. The apical portion of the aedeagal sac of the new species has six curved lateral spines on each side and three groups of short spines, while in C. biprojecta the lateroapical spines of the aedeagus ar e longer and hook-like, without more  spine groupings. In addition, the apical lobe of the aedeagus of C. changjiangensis sp. nov. is covered with distinct small spines, whereas in C. biprojecta it is bare.
Besides the distinctly diff erent armatures of the aedeagal sac, C. changjiangensis sp. nov. can easily be distinguished from the sympatric C. nigrifrons by external morphology: the anterolateral extension of the interocellar marking is moderately angled, not so rounded or heart-shaped as in C. nigrifrons; the hemitergal lobe is evenly tapering in lateral view, not like the medially abruptly tapering lobe in C. nigrifrons that could be observed both in dorsal and lateral aspects. Both of these characters were overlooked in previous studies (compare Sivec & Zwick 1989: fi g. 3b and Figs 1, 3B, D-E vs Figs 6B-E, 8A-B).  Chinoperla mengmanensis Qian & Du, 2012: 117, fi gs 1-5 (original description of the male).

Distribution
China: Yunnan Province, two localities in Mengla County.

Remarks
This species is characterized by the male aedeagus having a pair of spiny lateroapical lobes and a membranous apical lobe Chen & Hou 2020). The female subgenital plate is unproduced but with a pale semicircular posteromedial area, which was recently described by Chen & Hou (2020) from Mengla County of Yunnan.

Diagnosis
Head with a heart-shaped dark brown patch and a subtriangular dark brown spot. Male tergum 9 with a trumpet-shaped median sclerite. Hemitergal processes medially indented in lateral view. Aedeagal tube with a T-shaped sclerotized dorsal marking. Aedeagal sac dorsoapically with a low membranous median lobe; ventrobasally with a large patch of spinules; ventroapically with one long and one shorter spine, or the two of equal length; apically with a long straight spine and a large membranous lobe; laterally with dense large, curved spines arranged on each side. Posterior margin of female sternum 8 slightly produced, forming a small subtriangular subgenital plate with an apical notch.

Redescription Male
A (Figs 6A-B, 8C, 9A). General color brown. Forewing length 7.7-8.0 mm, hindwing length 6.7-7.1 mm. Head brownish, with a dark brown heart-shaped spot, but specimens from Mount Yinggeling with a long brown band located on the occiput, and with a subtriangular dark brown spot in front of M-line; biocellate, ocelli about 3 diameters apart of each other, slightly closer to each other than to the compound eye; antennae brown. Pronotum trapezoidal, brown with paler lateral margin and with darker, distinct rugosities; anterior corners pointed but posterior corners obtuse. Legs generally brown, proximal part of femora mostly lighter; wings subhyaline and brownish, veins brown, Sc of forewing short, typical of the genus (Fig. 8C); cerci brownish.
A (Figs 7, 10). Aedeagal tube partially sclerotized dorsally, forming a distinctly T-shaped marking on the holotype (Fig. 7A-B), but marking in specimens from Mount Yinggeling indistinct, well seen only in lateral view (Fig.10A-B). Fully everted sac as long as the tube, curved dorsad; ventroapical and dorsoapical surface heart-shaped in specimens from Mount Yinggeling (Fig. 10), less defi nite in the holotype (Fig. 7); dorsoapical surface with a small bulgy membranous me dian lobe; a single large spine about as long as ¼ aedeagus length, and a large membranous lobe medially at apex, slightly directed dorsally; ventral surface with a large basal patch of spinule, and one long and one shorter subapical spines (Fig. 7) but in fresh specimens from Mount Yinggeling the two of approximately equal length (Fig. 10); lateroapic al part with dense, large and curved spines arranged on each side.

Distribution
China: Hainan Province, found in three counties.

Remarks
We carefully compared the type specimens of O. nigrifrons deposited in MCZ with the illustrations in Sivec & Zwick (1989). The head pattern, direction of antennae and shape of the pronotum of the female paratype collected on 13 July 1935 are consistent with those illustrated in Sivec & Zwick (1989: fi g. 3a, d-e). The fi gures of the terminalia and vagina also refer to the same female paratype, because the second female paratype collected on 2 August 1935 had not been dissected, and its sternum 9 is more narrow. The fi gure of the male terminalia in Sivec & Zwick (1989: fi g. 3b) shows a shallow apical notch of the median sclerite of tergum 9, and tapering and curving hemitergal processes without a straight apical half. These characters are consistent with those in the male paratype, that is not conspecifi c with the holotype and has been reassigned to C. changjiangensis sp. nov. above (Fig. 3B-E). However, the small basal sclerite in the aedeagus of the holotype (Fig. 7B) corresponds to that illustrated in Sivec & Zwick (1989: fi g. 3c). Therefore, we believe that the half-everted aedeagus of the holotype, the terminalia of the male paratype (C. changjiangensis sp. nov.), and the head, pronotum, sterna 7-9 and vagina of the female paratype of Chinoperla nigrifrons were redescribed by Sivec & Zwick (1989). Color photographs and illustrations of the male holotype are provided in the present study (Figs 6-7). The characteristics of both female paratypes agree well with the description and illustrations provided by Sivec & Zwick (1989).
We checked the types of S. furcomacula in IZCAS, but the aedeagus of S. furcomacula with the holotype label was diffi cult to fully evert due to the poor condition of the specimen. Based on the original description and redescription of C. nigrifrons in the present study, we believe that the holotype of S. furcomacula is conspecifi c with the holotype of O. nigrifrons, and is therefore a junior synonym of C. nigrifrons (Banks 1939;Wu 1973;Sivec et al. 1988;Sivec & Zwick 1989). The two recently collected males from Hainan Province examined in this study agree well with the type specimens in general characteristics such as head pattern, lateral aspect of the hemitergal lobes, and armatures of the aedeagus. However, these fresh specimens from Mount Yinggeling show slight diff erences in the head pattern and aedeagus, as they have a long brown posterior band on the head, and the two ventroapical spines of the aedeagal sac are straight and nearly equal in length. We believe this brown occipital band disappears in fully aged adults, such as the holotype. Similar diff erences were documented in the case of Kamimuria guangxia Li & Wang, 2013and Neoperla lihuae Li & Murányi, 2014(Wang et al. 2013Li et al. 2014). The diff erences in the aedeagal armatures can be regarded as intraspecifi c diff erences. We provide illustrations of the fully everted sac of the C. nigrifrons holotype and the fresh adults to allow a reliable identifi cation for future studies (Figs 7, 10).
Unfortunately, the paratype female of S . furcomacula in IZCAS is badly damaged and diffi cult to study. According to the original description and fi gures of S. furcomacula (Wu 1973: fi g. 93), the terminalia of the paratype female distinctly diff er from those of C. nigrifrons by the unmodifi ed subgenital plate. Sivec & Zwick (1989) drew up three possibilities for the specifi c identity of this female; we support the third, which suggests that the paratype female may not be conspecifi c with the holotype of S. furcomacula. Further specimens from Hainan are needed to confi rm the identity of the female.  S inoperla nigrofl avata Wu, 1948: 78, fi gs 8-9 (original description of the male).

Distribution
China: Fujian Province, known only from the (now lost) holotype.

Remarks
The details of the aedeagal structures of this species are still unknown and the type material is lost Du et al. 1999;Yang & Li 2018). No new material was available for the present study, but it seems to diff er from the remaining Chinese species of Chinoperla based on the absence of the short Sc of the forewing and the shape of the dark median sclerite of tergum 9 : fi gs 8-9). Chinoperla gorohovi Sivec & Stark, 2010 from Guangdong and Vietnam is easily distinguishable from C. nigrofl avata by the slender nail-shaped median sclerite with a slightly enlarged apex (Fig. 11B-D). Sivec & Stark, 2010 Figs 11-14 Chinoperla gorohovi Sivec & Stark, 2010: 63, fi gs 1-4 (original description of the male).

D iagnosis
Head with a dark brown central spot subdivided by the lighter M-line. Male tergum 9 with a slender nailshaped median sclerite, having a slightly enlarged tip. Aedeagal tube with a fi shtail-shaped sclerotized dorsobasal marking. Aedeagal sac straight, dorsomedially with two diff erently sized membranous lobes, and apically with a membranous lobe bearing a long median spine and two shorter lateral spines. Posterior margin of female sternum 8 barely produced, f orming a small triangular subgenital plate. Eggs dark brown, teardrop-shaped with long and slender collar, and petiolate anchor.

Description
Male (complementary description) A (Fig. 11A). General color pale brown. Forewing length ca 9.5 mm, hindwing length ca 8.3 mm. Head pale brown, with a dark brown central spot subdivided by the lighter M-line; biocellate, ocelli about twice the diameter apart of each other, but still closer to each other than to the compound eye; antennal scape brown, fl agellum brownish. Pronotum pale brown, trapezoidal, with obscure darker rugosities and midline; anterior corners pointed but posterior corners obtuse. Legs brown but basal half of femora pale brown; wings subhyaline and yellowish brown, veins brown, Sc of forewing short, typical of the genus; cerci pale. A ( Fig. 11B-D). Sterna 3-5 with hair brushes. Dark median process of tergum 9 sclerotized, slender nail-shaped, about 3 times as long as wide, and slightly enlarg ed on posterior margin; posterior portion covered by several tiny, brown warts. Hemitergal processes slender, about 2.5 × as long as basal width, with a pointed tip; triangular in lateral view; basal callus with patch of sensilla basiconica. A (Fig. 12). Aedeagal tube partially sclerotized dorsobasally, forming a fi shtail-shaped marking. Fully everted sac as long as the tube, straight; a large and a small membranous lobe locat ed in dorsomedial portion, their apex points to the base and tip of the aedeagus, respectively; ventroapical surface with a slightly swollen and sclerotized area, distinct in lateral view; a basally sclerotized but mostly membranous apical lobe bears a long spine about as long as ¼ aedeagus length.  Female A (Fig. 13A). Forewing length ca 10.5 mm, hindwing length ca 9.5 mm. Habitus generally similar to the male. A (Fig. 13B-C). Subgenital plate of sternum 8 slightly produced, short but wide triangular, without mesal notch. E (Figs 13D-F, 14). Length 482-539 μm, width 226-232 μm (N = 5). Several mature eggs were dissected from female terminalia. Teardrop-shaped with long, slender collar and petiolate anchor. Anchor mushroom-shaped with marginal rows of globular bodies, pedicle stalked and hidden by anchor plate. Collar elongated and slender, with a short, fl anged rim. Chorion dark brown, covered with fi ne punctuations . Micropylar orifi ces sessile, much larger than punctuations, set on subequatorial line.

Distribution
Originally described from Tam Dao, Vietnam, and herein reported from China: Guangdong Province.

Remarks
The Chinese specimens are similar to the original description of Chinoperla g orohovi from northern Vietnam, in regards of head pattern, male terminalia, aedeagal tube, and the long apical spine of the aedeagal sac. However, the Chinese specimens diff er in having two membranous dorsomedial lobes on the aedeagal sac (compare Fig. 12A-B with Sivec & Stark 2010: fi g. 2). In the type specimens, the aedeagal sac apically has only one dorsal membranous lobe. In addition, the aedeagal sac of the Chinese specimens have an obscure, slightly sclerotized ventroapical patch, without a ventroapical spinose lobe, while in the type specimens, the aedeagal sac lacks the sclerotized ventroapical area, but has a short additional ventroapical spinose lobe. Unfortunately, the type specimens are permanently not available for study due to the re-organization of the Slovenian Museum of Natural History, Ljubljana (PMSL) collection (Ignac Sivec pers. com.).
presently known to be restricted to the south including Fujian, Guangdong, Hainan and Yunnan Provinces. The region is rich in diff erent types of surface waters, dominated by a tropical and subtropical monsoon climate, with high temperature and heavy rain in summer and less rain in mild winter. Due to the similar climate and environmental conditions, more members of the genus are expected in other provinces of the area, such as Guangxi, Guizhou, Hunan, Jiangxi and Zhejiang.
The male terminalia and aedeagus are regarded as the most important morphological characters in the taxonomic study of Chinoperla. As an important part of the male terminalia, the hemitergal processes of the members of the genus are usually slender and tapering to apex. The hemitergal processes of C. nigrifrons (Banks, 1939) are suddenly constricted at the apical half, forming an apical notch in lateral view. The notch is unique in the genus, distinguishing this species from others. The apical part of the aedeagus of species of Chinoperla usually bear lobes and spines, and some species have a ventroapical comb-shaped sclerite. The shape of the basal pattern, and the size and number of apical spines are also important features for identifi cation. The apical lobe of the aedeagus of the genus is large and membranous, bearing or lacking spines, and some species have more than one apical lobe, but this structure has sometimes been overlooked in previous studies. In addition, the head of Chinoperla is often covered by a large dark marking, and a triangular or subtriangular darker spot. The head pattern can be very similar, and its detailed features were often overlooked. The head pattern of C. nigrifrons is heart-shaped with a rounded apex, which is easily distinguishable from those of the congeners. According to the newly described or redescribed species in the present paper, we propose the use of the details of characteristics of the head pattern, apical lobe and spines of aedeagus, and hemitergal processes of tergum 10 in the delimitation of species of Chinoperla.